docs: def get_draft_secret_key():
      """
      Return the secret key used to generate draft mode HMACs. It will be
      randomly generated on first access. Existing draft URLs can be invalidated
      by deleting or updating the ``DRAFT_SECRET_KEY`` setting.
      """
      # TODO: Per URL secret keys, so we can invalidate draft URLs for individual
      #       pages. For example, on publish.
      draft_secret_key, created = Text.objects.get_or_create(
          name='DRAFT_SECRET_KEY',
          defaults=dict(
              value=get_random_string(50),
          ))
      return draft_secret_key.value